A CSIRO report released on Tuesday found that building 10 new water detention dams in New South Wales's northern rivers could have reduced flood levels by up to 2.1 metres during the devastating 2022 floods, but would not have prevented the Lismore CBD levee from being overtopped by 3.8 metres.
Report Findings and Government Response
The report, commissioned by the Morrison government four years ago, examined the one-in-100-years floods that struck the northern rivers between late February and early April 2022. The floods led to 13 deaths, left more than 4,000 properties uninhabitable, damaged another 10,849, and caused an estimated $16bn in socioeconomic and structural damage.
The state and federal governments have not committed to delivering the measures modelled in the report as part of the $11.4m Northern Rivers Resilience Initiative. Instead, they announced a joint $3m feasibility study on Tuesday.
CSIRO hydrologist Dr Jai Vaze, who led the report, said implementing the measures would likely depend on a business case, detailed architectural proposals, and environmental approvals. He noted that other flood resilience measures have already been implemented under $150m in federal funding.
Community Reactions
Lismore residents had mixed reactions to the findings. Matthew Gooley, operator of a family-run menswear business in the CBD since 1957, said the measures would be "amazing for Lismore" and could bring flood levels back to normal heights. Paul Morgan, owner of Lismore Computer Solutions, said he was "all for it if it works."
Marinda Hayward, left homeless by the 2022 floods, questioned spending $3m on a feasibility study and called for practical measures like keeping drains clean. Irene Guymer, whose daughter's farm flooded to nearly the second floor, said the measures would be a "waste of money" and suggested relocating the CBD to Goonellabah.
North Lismore artist and musician Jimmy Willing criticized the spending on the report and feasibility study while Lismore faces a housing crisis, saying, "It's a bit like putting men on the moon while people are starving."
Technical Details and Political Reactions
The CSIRO used hydrodynamic modelling to investigate two proposals: "Bundle 1" with five new water detention systems and upgrades, and "Bundle 2" with 10 water detentions across the Richmond Valley, Kyogle, Ballina, and Lismore LGAs. Dr Vaze preferred the term "water detentions" over "dams," as gates only close during floods.
Bundle 2 showed the greatest mitigation, potentially reducing water levels by up to 2.1 metres during the February 2022 flood (which peaked at 14.4 metres, the highest on record), 1.7 metres during a March 2022 flood, and 1.4 metres during 2017 floods, both of which would have remained below levee banks.
Federal minister for emergency management Kristy McBain and NSW counterpart Janelle Saffin welcomed the findings. Saffin said, "My reading of this report gives us real hope because it shows technically that flood levels can be lowered across all four local government areas."
However, NSW Greens upper house member Sue Higginson, a Lismore local, argued the report shows "billions of dollars in new dams for the Richmond River will not prevent severe flooding" and called for "planned retreat and nature-based solutions." Federal Nationals MP for Page Kevin Hogan said the report "details how flood mitigation could make our communities safer" and urged governments to act.
Context on Recovery Programs
Both Higginson and Hogan have criticized the rollout of the $100m Resilient Lands Program (RLP) and $880m Resilient Homes Program (RHP), the costliest disaster recovery program in Australian history. The RHP has bought back 813 properties as of this month, but a NSW auditor general's report found the RLP had yet to deliver a single home or lot after three and a half years.
